This invention relates to a support stand including a base, three legs secured to the base to extend radially therefrom and substantially equiangularly spaced from one another around the base and having a level adjusting mechanism, an outer pipe vertically extending from the base, an inner pipe telescopically movable in its axial direction relative to the outer pipe for adjusting the height of the support stand, locking means for locking the inner pipe against its telescopic movement relative to the outer pipe, and support means enabling the top of the inner pipe to mount thereon an article to be supported and having a mechanism for adjusting directions of the article in a horizontal plane.
There have been microphone stands, tripods for cameras or video cameras and the like as such a support stand mentioned in the first paragraph. In a microphone stand hitherto used, legs are connected to its base by screw threaded connection means to keep the legs at certain angles relative to the base. In another type of the microphone stand, a link mechanism is used for the purpose of extending and collapsing legs of the stand. In a further case, in order to adjust the height of a stand, after loosening a clamping sleeve, outer and inner pipes are adjusted in length by telescopically moving these pipes and then the clamping sleeve is again clamped to complete the adjustment of the height. In the other case, in order to adjust angles of a microphone in a horizontal plane, after loosening clamping screws for a holder attachment for supporting the microphone, the attachment is angularly adjusted in the horizontal plane and then fixed at the adjusted position by tightening the clamping screws.
With the support stands of the prior art, however, when the support stand is located on a floor partly different in height, it is impossible to set vertically a post consisting of an outer and an inner pipe, with the result that the stand becomes unstable tending to fall down. With the support stands of the prior art, moreover, for the purpose of adjusting their height by telescopically moving pipes constituting their post and adjusting their angles in horizontal planes, it is needed to loosen and then again tightening their clamping sleeves and clamping screws.
As can be seen from the above description, the support stands of the prior art suffer disadvantages from the difficulties in adjustment of verticality, height and angle in a horizontal plane and in holding an article to be supported in desired positions.
It is an object of the invention to provide an improved support stand which eliminates all the disadvantages of the prior art and which is able to adjust an article to be supported in height and angle in a horizontal plane in a simple manner and to hold the thus adjusted article in stable condition.
In order to accomplish the above object, locking means of the support stand according to the invention comprises a center bar concentrically arranged in said outer pipe and its lower end fixed to the lower end of said outer pipe; mesh sleeve means including a mesh sleeve slidably fitted about said center bar, upper and lower sliding bushes connected to upper and lower ends of said mesh sleeve, respectively, a coil spring arranged about said mesh sleeve between said upper and lower sliding bushes so that said mesh sleeve is axially elongated and radially contracted by the spring action of said coil spring to grasp said center bar by means of the mesh sleeve which is contracted and in close contact with said center bar, said lower sliding sleeve being fixed to the lower end of said inner pipe; a spacer sleeve arranged above said upper sliding bush and loosely fitted on said center bar and in said inner pipe; and an actuator sleeve provided around said inner pipe in the proximity of its upper end and connected to said inner pipe in a manner axially movable within a limited range with the aid of a cross pin passing through axially elongated apertures formed in diametrically opposed positions in said inner pipe in the proximity of its upper end so that said actuator sleeve in unloaded condition moves downward under the gravity force to the lowermost position where said cross pin becomes in contact with the upper end face of said spacer sleeve.
In a preferred embodiment of the invention, each of the legs is connected to the base to be pivotally movable about a horizontal axis between a collapsed position substantially parallel to the axial direction of the outer pipe and an extended position extending substantially radially outwardly, and the level adjusting mechanism comprises a hood portion for each of the legs provided on the base and radially extending in the extending direction of the leg to overhang the top surface of the leg and a stopper screw head provided on the top surface of the each leg on the side of its proximal end pivotally connected to the base and adjustable in height in the direction perpendicular to the leg axis and engageable with the inclined lower surface of the hood portion.
In another preferred embodiment of the invention, the support means comprises a stationary sleeve connected with its lower end to the top of the inner pipe by means of screw threads; a torque adjusting bolt extending upward with its upper end beyond the stationary sleeve and having a head engaging a seat provided on the stationary sleeve; a movable head screw-threadedly engaging a threaded portion of the torque adjusting bolt and having a knurl portion and an externally threaded portion for anchoring a holder of an article to be supported; elastic friction engagement means arranged between the stationary sleeve and the movable head and having a bore through which the torque adjusting bolt passes; and a torque fixing nut arranged in a recess formed in the externally threaded portion of the movable head to expose the upper end of the tongue adjusting bolt and screw-threadedly engaging the exposed upper end of the torque adjusting bolt.
With the locking means of the support stand according to the invention different from the clamping means using screw threads of the prior art, when the inner pipe is moved upward relative to the outer pipe by raising the actuator sleeve located at the upper end of the inner pipe, the lower sliding bush of the mesh sleeve means connected to the lower end of the inner pipe slides upwardly along the center bar fixed to the outer pipe. The upward sliding movement of the lower sliding bush causes the radially contracted mesh sleeve to be loosened or radially expanded, while the coil spring causes the upper sliding bush to move upward. When the actuator sleeve is released, the mesh sleeve in this position is axially elongated and radially contracted by the action of the coil spring so as to be in close contact with the center bar to hold this state of the inner and outer pipes.
Next, when the actuator sleeve is moved downward to move the inner pipe downward into the outer pipe, the cross pin of the actuator sleeve moves the upper sliding bush downward with the aid of the spacer sleeve against the action of the coil spring. Therefore, the mesh sleeve radially expands so that the mesh sleeve, the lower sliding bush and the inner pipe move downward along the center bar fixed to the outer pipe. Upon releasing the actuator sleeve, the mesh sleeve is again axially elongated and radially contracted by the action of the coil spring so as to be in close contact with the center bar to stop at this position automatically, thereby holding this condition of the support stand.
According to the support stand of the invention, by adjusting the height of the stopper screw head provided at the upper face of each of the legs on its mounting side to the base, the stopper screw head will engage the inclined lower surface of the hood portion of the base to determine the open angle of the leg before the leg arrives at the fullest extended position. Open angles of the two remaining legs are also determined in the same manner so that the support stand can be vertically settled even the floor is uneven or stepped, as a result of which an article on the support stand is supported in stable condition.
According to the support means of the support stand of the invention, moreover, in order to adjust the sliding engagement strength of the elastic friction engagement means, the axial position of the movable head relative to the torque adjusting bolt is adjusted, and in order to fix the movable head at the adjusted position, the torque fixing nut is connected to the upper end of the torque adjusting bolt by means of screw threads, whereby the torque adjusting bolt, the movable head and the torque fixing nut are integrally united into a head assembly. In this manner the head assembly is rotated in unison relative to the stationary sleeve with a torque in excess of the adjusted torque, thereby holding the article on the support stand in the rotatively adjusted position in the horizontal plane.
The invention will be more fully understood by referring to the following detailed specification and claims taken in connection with the appended drawings.